In recent years, with the development of network systems, a network communication device for sending and receiving e-mail via a network such as the Internet is used for various purposes.
For example, a network communication device with a scanning function has been created, which is capable of not only scanning an image but also sending the scanned image information to a device such as a computer connected to a network.
Further, a network facsimile device with a printing function or a telephone function in addition to the scanning function has been created.
An internet fax, as an example of the foregoing network facsimile device, is connected to a provider of the Internet via a telephone line so as to be connected to the Internet via the host computer of the provider of the Internet, or is directly connected to the Internet. With this state, sending and receiving of e-mail are carried out with an internet fax of the sending end and an internet fax of the receiving end, which are both connected to the Internet.
Unlike the case of sending information by a general facsimile, when thus sending information by using e-mail, there has been such a problem that the sending end cannot judge if the receiving has properly completed in the receiving end, and also if receiving operation has properly performed in the receiving end.
More specifically, unlike the case of using a G3 facsimile carrying out facsimile communication in real time at respective ends via PSTN (Public telephone network), when e-mail is sent from the sending end terminal to the receiving end terminal, the sending end terminal cannot recognize if the receiving of e-mail has properly completed in the receiving end terminal, and if receiving operation has properly performed in the receiving end terminal at the time of transmitting e-mail.
Therefore, conventionally, confirmation of the transmission by telephone has still been required when carrying out e-mail communication.
As described, even when sending information by e-mail, the user still has to take a trouble of confirming the transmission by using telephone. Therefore, the foregoing manner cannot provide the benefit of e-mail communication, which is supposed to enable the user to omit the trouble of real time conversation in contrast to telephone communication.
In order to solve the foregoing problem, RFC2298 regulates the method of MDN (Message Disposition Notification) as a method for confirming transmission by sending back a response for informing completion of the transmission to the sending end terminal from the receiving end terminal when e-mail is received in the receiving end terminal device.
The RFC (Request For Confirmation) is an official document published by the IETF (Internet Engineering Task Force), which is an organization for determining standards of technology regarding the Internet.
One example of the RFC has various protocols used in the Internet, such as IP (Internet protocol), TCP (Transmission Control Protocol), HTTP (Hypertext Transfer Protocol) and FTP (File Transfer Protocol), and also includes specification and requirements of a variety of technologies regarding the Internet. The RFC is published with a serial number, such as the foregoing RFC2298.
Japanese Unexamined Patent Publication No. 309109/2001 (published on Nov. 2, 2001) discloses an internet fax (a network communication device) having the described MDN function. This internet fax outputs a record of failure of transmission to the user when a MDN response e-mail is not sent from the receiving end after a certain period of time after completion of transmission, so as to inform the user that delivery of the MDN response (transmission confirmation response) has not been made.
With this function, it is possible to confirm whether or not the transmission is properly completed in the receiving end terminal.
However, the foregoing MDN function is not a compulsory function of a network communication device for carrying out communication via a network. Accordingly, the receiving end terminal is not always provided with the MDN function.
Thus, in the configuration requiring the MDN function at each time of communication as with the internet fax disclosed in the foregoing publication, if the receiving end terminal is not provided with the MDN function, the sending end unnecessarily has to wait for the MDN response since the receiving end terminal will not send the MDN response even when transmission of the e-mail is properly completed.
Further, since the receiving end terminal is not provided with the MDN function, the sending end terminal will output an unnecessary record of failure of transmission even when the transmission is completed in the receiving end terminal.